The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Traditional lighting control systems refer to the time-clock and the lighting switch, both of which have only two states: on and off. They are very simple and easy to install by electricians prior to installing lighting fixtures (or lighting devices) with which they are connected by hot wire and neutral wire.
In the past 10 years, we have seen the importance of green building making way for green building as today's standard. One of the major requirements of the green building standard is energy usage for lighting devices. Initially, the standard only applies to the energy rating of the lighting fixtures, but gradually, the standard began to outline detailed lighting control requirements. For example, the standard imposes that lighting devices in the daylight zone must be automatically dimmed by available ambient lights, lighting devices in small offices and conference rooms must be controlled by occupancy sensor; lighting devices in the corridor and parking garage must be dimmed by occupancy sensor. Due to these requirements, sophisticated lighting control systems were developed.
The key component for lighting control systems is the dimming portion. It is the device for modulating the electrical current to the lighting fixtures or the duty cycle, in order to control the luminance of the lighting fixtures. A majority of manual dimmers, such as Triode for Alternating Current (TRIAC), use resistor-capacitor circuits to adjust the duty cycle. U.S. Patent Publication 2004/0212321 to Lys et al. titled “Methods and Apparatus for Providing Power to Lighting Devices,” filed May 9, 2003 discloses a dimming circuit using TRIAC.
Unfortunately, existing TRIAC types of dimmers only allow for manual dimming. For automatic dimming, current state of the art system uses electronic controller that requires device-specific drivers for different lighting fixtures. The driver can get modulated power from the central electronic controller to adjust luminance of the lighting fixtures. The central controller is powered from the electrical panel, and can collect signals from all the connected sensors (e.g., luminance sensors, occupancy sensors, etc.). Based on the settings, the central controller modulates the power electronically and sends the modulated power to the drivers. U.S. Pat. No. 5,406,176 issued to Sugden titled “Computer Controlled Stage Lighting System,” filed Jan. 12, 1994 discloses an example of such an electronic dimming control system.
Other efforts that contributed to this field include:                U.S. Pat. No. 5,789,869 to Lo et al. titled “Light Sensitive Dimmer Switch Circuit,” filed Sep. 17, 1996;        U.S. Pat. No. 7,336,041 to Ayala et al. titled “Automatic Light Dimmer for Electronic and Magnetic Ballasts (Fluorescent or HID),” filed Oct. 27, 2005;        U.S. Pat. No. 8,497,636 to Nerone titled “Auto-Switching TRIAC Compatibility Circuit with Auto-Leveling and Overvoltage Protection,” filed Mar. 11, 2011; and        U.S. Patent Publication 2005/0128752 to Ewington titled “Lighting Module,” filed Oct. 20, 2004.        
The above explanation, the current systems have three major parts: drivers, controllers, and sensors. These systems all have lighting fixtures that do not receive power from the electrical panel directly but are fed from the central electronic controller through a device-specific driver. The controller and device-specific drivers are necessary, and the controller's capacity governs the number of lighting fixtures to be controlled by the sensors and switches.
These prior art lighting control systems, however, are dependent on the configuration on the controller. Therefore, the system must be installed and configured by electricians who are experienced and knowledgeable about these new types of central controllers. The driver, as the interface between the lighting fixture and the controller, must be compatible with the lighting fixtures and follow the controller′ protocol. As such, in order to successfully implement these lighting dimming systems, the components must be very carefully selected, which requires a lot of coordination among electrical designers, control system vendors, light fixture vendors, and electricians during the construction of the building.
Thus, there is a need to provide a simple automatic lighting control system that can be installed and serviced easily by traditionally trained electricians.